Revert "chromeos_config: Use latest toolchain in lakitu_next"

This reverts commit 6e6b9f03571912b323aff7417216e59b6c147848.

Reason for revert: This was needed in order to validate go-1.10 upgrade. Now the validation is finished, it's not necessary to make lakitu_next always build with the latest toolchain.

Original change's description:
> chromeos_config: Use latest toolchain in lakitu_next
>
> This CL makes lakitu_next to always use the latest toolchain
> to build. So that we can test go-1.10 on lakitu_next.
>
> BUG=b:77822693
> TEST=trybot
>
> Change-Id: Icecad19177262e7de52d17763b585bae80fbeaa7
> Reviewed-on: https://chromium-review.googlesource.com/1011546
> Commit-Ready: Ke Wu <mikewu@google.com>
> Tested-by: Ke Wu <mikewu@google.com>
> Reviewed-by: Don Garrett <dgarrett@chromium.org>

Bug: b:77822693
Change-Id: Ib71926224c10844e40384b5e62391549e76f62c6
Reviewed-on: https://chromium-review.googlesource.com/1023170
Commit-Ready: Ke Wu <mikewu@google.com>
Tested-by: Ke Wu <mikewu@google.com>
Reviewed-by: Daniel Wang <wonderfly@google.com>
Reviewed-by: Rahul Chaudhry <rahulchaudhry@chromium.org>
2 files changed